dopecalc

Amortization Calculator

Generate a complete amortization schedule for any loan. See payment-by-payment breakdown of principal, interest, and remaining balance.

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About this Calculator

Generate a complete amortization schedule for any loan. See payment-by-payment breakdown of principal, interest, and remaining balance.

Formula & Calculations

Formula

M = P [ r(1+r)^n ] / [ (1+r)^n - 1 ]
Where:
  • M=Monthly payment amount
  • P=Principal loan amount
  • r=Monthly interest rate (annual rate / 12)
  • n=Total number of monthly payments

Assumptions

  • Assumes fixed interest rate for the entire loan term.
  • Each payment is applied to interest first, then principal.
  • No additional payments, prepayments, or fees are considered.

Calculation Examples

Example 1

Inputs:Loan: $200,000, Rate: 6%, Term: 30 Years
Result:Monthly Payment: $1,199.10, Total Interest: $231,676.38, Total Cost: $431,676.38

A 30-year $200,000 mortgage at 6% costs $1,199.10 monthly, with over $231,000 in total interest — more than the original loan amount.

Example 2

Inputs:Loan: $30,000, Rate: 8%, Term: 5 Years
Result:Monthly Payment: $608.29, Total Interest: $6,497.40, Total Cost: $36,497.40

A 5-year personal loan of $30,000 at 8% has 60 payments of $608.29 each. Early payments are mostly interest; later payments are mostly principal.

Example 3

Inputs:Loan: $15,000, Rate: 12%, Term: 3 Years
Result:Monthly Payment: $498.21, Total Interest: $2,935.69, Total Cost: $17,935.69

Higher interest rates dramatically increase total cost even on shorter term loans.

Frequently Asked Questions

What is amortization?

Amortization is the process of spreading a loan into a series of fixed payments over time. Each payment covers both interest and principal, with the portion going toward principal increasing over time while the interest portion decreases.

How can I pay off my loan faster?

Make extra principal payments whenever possible, switch to bi-weekly payments (resulting in one extra full payment per year), or consider refinancing to a shorter term at a lower interest rate. Always confirm there are no prepayment penalties first.